Improvement in balanced valves for steam-engines



C. H. PARSHALL. BALANCED VALVES FOR STEAMENGINES.

No. 40,796. I PATENTED DEC. 1, 1863.

UNITED STATES PATENT ()FFICE.

CHARLES H. PARb'H ALL, OF llE'lltOYI, Ml ClHG AN, ASSIGNOR TO PARSHALL AND DUNCAN.

IMPROVEMENT IN BALANCED VALVES FOR STEAM-ENGINES.

S ecificamen-mrmfng part of Letters rate'nt No. 40,.7Ql5, d'u'ted December 1, 1863.

To all whom it may concern:

Be it known that 1, CHARLES H. PARSHA LL, of the city of Detroit, in the county of \Vayne,

V n in drawin s, and to the letters of reference marked thereon, forming a part of this specification, in which Figurei is. avertical section, A B, of steam chest and cylinder, showing my invention. Fig. 2 is a vertical cross-section, C D,ofsteumcylinder and steam-chest, also showing my invention. Fig. 3 isa horizontal section, E F, of steam-chest; Fig. 4 is a plan or top view of the steam-chest when its cover H is removed, showing my invention in part.

Similar letters of reference in the four figures indicate corresponding parts.

The nature of my invention consists in providing a slide steam-valve used for letting steam in and out of the cylinders ofsteamengines which will at the same time be balanced both as to the steam and atmospheric pressure on it, and, in cases where the valve moves upon a horizontal orinelined seat,will be also balanced as to'its pressure on the valveseat from its own weight, whereby I do away with a large amount of friction; also require much less steam-power to perform a given amount of work, and also diminish the natural wear of the machinery.

To enable others skilled in the art to make and use my invention, I will proceed to describe its construction and operation.

I construct my valve 0 and valveseat P in the well-known common modes and forms, the valve having in it the usual exhaustconcave, and making asteam tight joint with the valve seat. and the valve-seat having two ports, U.

U, for letting thesteamiu and out of the cylinder B, one for each end of cylinder, and an exhaust-port, S. for carrying it off after its use in cylinder. I also cut off the st'cam from cylinder in the well known modes at full stroke of the piston, or less, as may be desired. I also. give the valve its motioh in any wellknown mode by means of a valve-rod, N, to which it is fastened.

By means of connecting-stamlards K K K K and screws, or by any other convenient mode and means, I fasten firmly to and over the valve and parallel to its lower surface the plate V, of suitable thickness and strength, and of the same upper surface area as the plane lower surface area of the valve, and this plate may-also be so fastened by casting it in connection with the valve. \Vheu thus fastened, the plate V and valve will move in connection with each otheras one body. On this plate V, I place a plate, J, of suitable thickness and strength, having in it an aperture, \V, of an area hereinafter to be described, and resting at its corners on the standards L L L-' L. By grinding or otherwise, I make a steam-tight joint of thelower face of the plate. J with the upper face of the plate V. I constrnct the sides I of the steamchest to come up even with the upper surface of the plate .J, and fit to its sides the plate J, as near steamtight as practicable.

I place a cover, H, of suitable thickness and I strength over the plate J and its joint with the sides of the steam-chest. I cover such joint with a gasket to aid in making it steamtight, and fasten the cover 11 firmly to the sides of the steam-chest by screws or otherwise. In the center of the cover H, and over the aperture \V in plate J, I make. a small aperture, G, of suitable size for the purpose, so as to connect the aperture W in plate J with the surrounding atmosphere, and allow its free and natural pressure upon the plate V.

By means of a gasket or other filling be-' tween the plate J and cover H, and, ifdesired, by the further means of casting the plate J with sunken panels, I create thin air: chambers Z Z between the plate J and cover 11. These air-chambers will aid in preserving calorie and also an equality of temperature.

the rise of warm and descent of cold air through the aperture G, also in preserving an equality of temperature, and also to serve as a cover to such aperture G, and at the same time allow the aperture \V to have its free communication with the surrounding atmosphere, I lit and fasten firmly to the aperture (1 one end of a small tube or pipe, Y, which I make 'open at each end, with a curved turn. and so To aid in preventing the loss of caloric by as to bring the other end down and near to the cover ll.

If lubrication is desired for such purpose,I insert in the cover 11-, over the aperture Win plate J ,a cock with oil-cup attached according the usual mode.

By means of the plate V fastened to the valve 0, and making a steal'n-tight joint with the plate J, as herein deseribed,thestcam does not press on the upper surface of the plate V, and by means of the lower surface of the valve making a steam-tight joint with the valveseat, the steam does not press on the lower surface of the valve, and Ithusbalance the valve, as to the steam pressure on it, so

that such pressure does not force it against the valve-seat P or against the plate J. The

'valve being still unbalanced as to the pressure of the atmosphere, which acts against its lower surface through the exhaust-port S, and thusforces the plate V against the plate J, and the valve being also still unbalanced as to its pressure from its own weight, which forces it against the valve-scat, I overcome these forces and balancethe valve as to them in the following mode: By means of the aperture W in plate J, and its free communication with the surrounding atmosphere, as herein described, so much of the upper surface of plate V as is exposed to the aperture W, I subject to the pressure of the atmosphere as an opposing force to the like pressure on the lower surface of the valve. Now, in order to balance the valve both as to the atmospheric pressure on its lower surface and the pressure of the valve on its seat from its own weight, I make the area of the aperture WV in plate J of such dimensions as will expose to the atmospheric pressure so much area of the upper surface of plate V as will be equivalent to the area of.

the lower su rface of the valve exposed to the like opposite pressure, deducting, however, from such first-mentioned area a proportion thereof the atmospheric pressure on which will be equivalent to the pressure of the valve on. its seat from its own weight. In cases where the valve moves on a perpendicular seat no such deduction is to be made. and where it moves on an inclined seat such proportion to be deducted will vary under varying angles of inclination and the consequent varying pressures of the valveon its seat from its own weight.

In'the modes above shown 1 balance my valve as to the steam and atmospheric pressures on it, and also as to itspressure on its seat from its own weight, and thereby do away with a large amount of friction on the valve, valve-seat, and other parts of the engine. I also do away with the increase of steam used to overcome the friction thus done away with, and I also do away with the wear of the machinery naturally caused by the friction thus done away with and by the increase of steam to overcome it.

'Letters of reference are marked on the acjcompariying drawings, not before referred to,

as follows, viz: Q being the steam-pipe as it enters the steam-chest, '1 being the gland of thestufiing-box of the valve-rod N, X X being nuts for fastening the cover H\to sides I of steam-chest, M M being nuts for fastening the valve-rod N to the valve 0 What I claim as my invention, and desire to secure by Letters Patent, is-

1. The plate J ,interposed between the-valve O V and the cover H of the valve-chest and supported by standards L L L L, substantially as herein shown and described.

2, The combination of the balanced valve 0 V, )late J, cover H, and curved pipe Y, all constructed, arranged, specified.

Dated at Detroit this 2d day of November, A. D. 1863.

CHARLES H, PARSHALL.

Witnesses:

ALEX. W. BUEL, J OHN ISAAOS.

and operating as, 

